A few years back the main dealers brought over a raft of ex UK cars, the Sterling Collection, when no one was buying new cars here. I suspect they may be less inclined to bother doing it now. Stg exchange rates and the fact that people are buying new again may mean they couldn't be bothered now, but it can do no harm to ask. However they likely do have access to the inventory of BMW UK Group businesses that coordinate some of the used car supply to dealers from BMW management cars, Finance, Leasing, etc. (this was the supply chain for Sterling Collection).